National Institutes of Health. Third Report of the National Cholesterol Education
Program Expert Panel on Detection, Evaluation, and Treatment of High Blood
Cholesterol in Adults (Adult Treatment Panel III). Bethesda, Md: National Institutes of Health; 2001. NIH Publication
01-3670.

Centers for Disease Control and Prevention. The Third National Health and Nutrition Examination
Survey (NHANES III 1988-94) Reference Manuals and Reports [CD-ROM]. Bethesda, Md: National Center for Health Statistics; 1996.

Alberti KG, Zimmet PZ. Definition, diagnosis and classification of diabetes mellitus and its
complications, part 1: diagnosis and classification of diabetes mellitus provisional
report of a WHO consultation. Diabet Med.1998;15:539-553.

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Citation

Ford ES, Giles WH, Dietz WH. Prevalence of the Metabolic Syndrome Among US AdultsFindings From the Third National Health and Nutrition Examination Survey. JAMA. 2002;287(3):356-359. doi:10.1001/jama.287.3.356

Prevalence of the Metabolic Syndrome Among US AdultsFindings From the Third National Health and Nutrition Examination Survey

Author Affiliations: Division of Nutrition and Physical Activity (Drs Ford and Dietz) and the Division of Adult and Community Health (Dr Giles), National Center for Chronic Disease Prevention and Health Promotion, Centers for Disease Control and Prevention, Atlanta, Ga.

Context The Third Report of the National Cholesterol Education Program Expert
Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in
Adults (ATP III) highlights the importance of treating patients with the metabolic
syndrome to prevent cardiovascular disease. Limited information is available
about the prevalence of the metabolic syndrome in the United States, however.

Objective To estimate the prevalence of the metabolic syndrome in the United States
as defined by the ATP III report.

Design, Setting, and Participants Analysis of data on 8814 men and women aged 20 years or older from the
Third National Health and Nutrition Examination Survey (1988-1994), a cross-sectional
health survey of a nationally representative sample of the noninstitutionalized
civilian US population.

Main Outcome Measures Prevalence of the metabolic syndrome as defined by ATP III (≥3 of
the following abnormalities): waist circumference greater than 102 cm in men
and 88 cm in women; serum triglycerides level of at least 150 mg/dL (1.69
mmol/L); high-density lipoprotein cholesterol level of less than 40 mg/dL
(1.04 mmol/L) in men and 50 mg/dL (1.29 mmol/L) in women; blood pressure of
at least 130/85 mm Hg; or serum glucose level of at least 110 mg/dL (6.1 mmol/L).

Results The unadjusted and age-adjusted prevalences of the metabolic syndrome
were 21.8% and 23.7%, respectively. The prevalence increased from 6.7% among
participants aged 20 through 29 years to 43.5% and 42.0% for participants
aged 60 through 69 years and aged at least 70 years, respectively. Mexican
Americans had the highest age-adjusted prevalence of the metabolic syndrome
(31.9%). The age-adjusted prevalence was similar for men (24.0%) and women
(23.4%). However, among African Americans, women had about a 57% higher prevalence
than men did and among Mexican Americans, women had about a 26% higher prevalence
than men did. Using 2000 census data, about 47 million US residents have the
metabolic syndrome.

Conclusions These results from a representative sample of US adults show that the
metabolic syndrome is highly prevalent. The large numbers of US residents
with the metabolic syndrome may have important implications for the health
care sector.

People with the metabolic syndrome are at increased risk for developing
diabetes mellitus1 and cardiovascular disease2 as well as increased mortality from cardiovascular
disease and all causes.3 The recently released
Third Report of the National Cholesterol Education Program Expert Panel on
Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult
Treatment Panel III) (ATP III) draws attention to the importance of the metabolic
syndrome and provides a working definition of this syndrome for the first
time.4 The prevalence of the metabolic syndrome
as defined by ATP III in the United States is unknown. Because the implications
of the metabolic syndrome for health care are substantial, we sought to establish
the prevalence of this condition.

METHODS

Between 1988 and 1994, a representative sample of the civilian noninstitutionalized
US population was recruited into the Third National Health and Nutrition Examination
Survey (NHANES III) using a multistage, stratified sampling design.5,6 After an interview in the home, participants
were invited to attend 1 of 3 examination sessions: morning, afternoon, or
evening.

As detailed in the ATP III report, participants having 3 or more of
the following criteria were defined as having the metabolic syndrome:

Abdominal obesity: waist circumference >102 cm
in men and >88 cm in women;

We counted participants who reported currently using antihypertensive
or antidiabetic medication (insulin or oral agents) as participants with high
blood pressure or diabetes, respectively. Serum triglycerides were measured
enzymatically after hydrolyzation to glycerol (Hitachi 704 Analyzer; Hitachi,
Tokyo, Japan). High-density lipoprotein cholesterol was measured following
the precipitation of other lipoproteins with a heparin-manganese chloride
mixture (Hitachi 704 Analyzer). Serum glucose concentration was measured using
an enzymatic reaction (Cobas Mira assay; Roche, Basel, Switzerland). Details
about the laboratory procedures of all these tests are published elsewhere.6 Three blood pressure readings were obtained in the
mobile examination center. The average of the second and third systolic and
diastolic blood pressure readings were used in the analyses.

For men and nonpregnant women aged at least 20 years who attended the
medical examination and who had fasted at least 8 hours, we calculated the
prevalence of the metabolic syndrome by age, sex, and race or ethnicity (white,
African American, Mexican American, other). We calculated estimates using
the sampling weights so that the estimates are representative of the civilian
noninstitutionalized US population. All analyses were done by using SUDAAN
to obtain proper variance estimates because of the complex sampling design.7

RESULTS

Among men, whites and Mexican Americans had the highest age-adjusted
prevalences of abdominal obesity, hypertriglyceridemia, and low HDL cholesterol
concentration (Table 1). African
American men had the highest age-adjusted prevalence of hypertension, and
Mexican American men had the highest age-adjusted prevalence of hyperglycemia.
Among women, Mexican Americans and African Americans had the highest age-adjusted
prevalence of abdominal obesity. African American women had the highest age-adjusted
prevalence of high blood pressure, and Mexican American women had the highest
age-adjusted prevalences of hypertriglyceridemia, low HDL cholesterol concentration,
and hyperglycemia.

Overall, the unadjusted and age-adjusted prevalences of the metabolic
syndrome were 21.8% and 23.7%, respectively (Table 2). The prevalence increased from 6.7% among participants
aged 20 through 29 years to 43.5% and 42.0% for participants aged 60 through
69 years and 70 years or older, respectively (Figure 1). The prevalence differed little among men (24.0%) and
women (23.4%). It was highest among Mexican Americans (31.9%) and lowest among
whites (23.8%), African Americans (21.6%), and people reporting an "other"
race or ethnicity (20.3%). Among whites and participants of the other race
or ethnic group, men and women had a similar prevalence of the metabolic syndrome
(Figure 2). Among African Americans,
women had about a 57% higher prevalence than men did. Among Mexican Americans,
women had about a 26% higher prevalence than men did. Application of the age-specific
prevalence rates to US census counts from 2000 suggests that 47 million US
residents have the metabolic syndrome.

COMMENT

Using ATP III's new definition, we estimate that approximately 22% of
US adults (24% after age adjustment) have the metabolic syndrome. Previous
estimates of the prevalence of the metabolic syndrome in the United States
and Europe have differed because of differences in definitions and populations
studied.2,8- 16
The unrelenting increase in the prevalence of obesity in the United States17 suggests that the current prevalence of the metabolic
syndrome is now very likely higher than that estimated from 1988-1994 NHANES
III data. Even if prevalence rates remained unchanged, the total number of
people with the metabolic syndrome would have increased because of population
growth during the 1990s.

Insulin resistance is thought to be an underlying feature of the metabolic
syndrome.18 Genetic abnormalities, fetal malnutrition,
and visceral adiposity may play roles in the pathophysiology of insulin resistance
and the metabolic syndrome.19 Although insulin
resistance among patients with the individual components of the metabolic
syndrome is common, significant proportions of these patients do not have
insulin resistance. Some studies have suggested that hypertension is not strongly
linked to the metabolic syndrome.20

The cornerstones of treatment are the management of weight and ensuring
appropriate levels of physical activity. Recent studies demonstrate that dietary
modification and enhanced physical activity may delay or prevent the transition
from impaired glucose tolerance to type 2 diabetes mellitus and provide relevant
treatment paradigms for patients with the metabolic syndrome.21- 23
While proper management of the individual abnormalities of this syndrome can
reduce morbidity and mortality, it seems unlikely that management of the individual
abnormalities of this syndrome provides better outcomes than a more integrated
strategy.

Education and training will be critical to ensure that health care providers
have the knowledge and skills necessary to properly treat patients with the
metabolic syndrome. Lack of reimbursement for weight management and physical
activity interventions constitutes a major barrier. Significant efforts are
needed to close the gap between current and desirable practice patterns.

The high prevalence of this condition may also have serious implications
for US health care costs. Thus, studies of the direct medical costs associated
with the metabolic syndrome are urgently needed. Because the root causes of
the metabolic syndrome for the overwhelming majority of patients are improper
nutrition and inadequate physical activity, the high prevalence of this syndrome
underscores the urgent need to develop comprehensive efforts directed at controlling
the obesity epidemic and improving physical activity levels in the United
States.

National Institutes of Health. Third Report of the National Cholesterol Education
Program Expert Panel on Detection, Evaluation, and Treatment of High Blood
Cholesterol in Adults (Adult Treatment Panel III). Bethesda, Md: National Institutes of Health; 2001. NIH Publication
01-3670.

Centers for Disease Control and Prevention. The Third National Health and Nutrition Examination
Survey (NHANES III 1988-94) Reference Manuals and Reports [CD-ROM]. Bethesda, Md: National Center for Health Statistics; 1996.

Alberti KG, Zimmet PZ. Definition, diagnosis and classification of diabetes mellitus and its
complications, part 1: diagnosis and classification of diabetes mellitus provisional
report of a WHO consultation. Diabet Med.1998;15:539-553.